1. Field of the Invention
The present invention relates to a thin-film magnetic head having a magnetoresistive effect element using the magnetoresistive effect of a spin valve film or the like. More particularly, the present invention relates to a thin-film magnetic head giving an improved electrical insulation between the electrode layer of the magnetoresistive effect element and the lower shielding layer, and a manufacturing method thereof.
2. Description of the Related Art
FIG. 21 is an enlarged sectional view illustrating a conventional thin-film magnetic head as viewed from the opposite side of a recording medium (i.e., from the xe2x80x9cABSxe2x80x9d or air bearing surface plane) In FIG. 21, symbols X,Y and Z represent an X coordinate axis, a Y coordinate axis, and a Z coordinate axis, respectively.
This thin-film magnetic head is a read head using the magnetoresistive effect, formed on a trailing side end surface of a slider constituting, for example, a floating-type head. The thin-film magnetic head may be a head formed by laminating a write inductive magnetic head on the aforementioned read head, known generally as an MR(magnetoresistive)/inductive composite thin-film magnetic head.
In FIG. 21, the reference numeral 1 represents a lower shielding layer formed from Sendust or an NiFe alloy (permalloy), and a lower gap layer 4 made of a non-magnetic material such as Al2O3 (alumina) is formed on the lower shielding layer 1. A magnetoresistive effect element 5 is formed in the form of a film on the above-mentioned lower gap layer 4. A multilayer film 6 using the magnetoresistive effect is formed at the center of the magnetoresistive effect element 5.
The aforementioned multilayer film 6 comprises a spin-valve film (a type of xe2x80x9cGMRxe2x80x9d or giant magnetoresisitve element) having, for example, an anti-ferromagnetic layer, a fixed magnetic layer, a non-magnetic conductive layer, and a free magnetic layer. In this spin-valve film, magnetization of the fixed magnetic layer is fixed in a direction perpendicular to the plane of the drawing (Y-direction: height direction), and magnetization of the free magnetic layer is aligned with the track transverse direction (X-direction). When the magnetic field from the recording medium penetrates in the direction perpendicular to the plane of drawing, magnetization of the free magnetic layer varies, and electric resistance varies under the effect of the relationship between fixed magnetization of the fixed magnetic layer and varying magnetization of the free magnetic layer, thus reproducing the magnetic field of the recording.
As shown in FIG. 21, a hard bias layer 7 and an electrode layer 8 made of a non-magnetic conductive material having a low electric resistance such as Cr (chromium) or Ta (tantalum) are formed as a longitudinal bias layer on each side of the multilayer film 6.
An upper gap layer 9 is formed on the magnetoresistive effect element 5, and further, an upper shielding layer 10 is formed on the upper gap layer 9.
Also as shown in FIG. 21, the lower gap length GL1 is determined from the thickness of the lower gap layer 4 formed under the magnetoresistive effect element 5, and the upper gap length GL2 is determined from the thickness of the upper gap layer 9 formed on the magnetoresistive effect element 5. The read gap length GL is set from the thickness of the magnetoresistive effect element 5, the lower gap length GL1 and the upper gap length GL2.
FIG. 22 is a plan view of the magnetoresistive effect element 5 formed on the lower gap layer 4. As shown in FIG. 22, the multilayer film 6 and the electrode layer 8 forming the magnetoresistive effect element 5 are exposed to the ABS plane serving as an opposite surface to the recording medium, and the electrode layer 8 extends to the rear side (Y-direction: height direction) from the multilayer film 6. The electrode layer 8 is formed so as to become larger in width toward the rear side.
Along with the recent tendency toward a higher recording density, it is necessary to form the lower gap length GL1 and the upper gap length GL2 shown in FIG. 21 into smaller sizes.
However, when the gap layers 4 and 9 are formed into smaller thickness with a view to reducing the sizes of the lower gap length GL1 and the upper gap length GL2, defects such as pinholes are produced in the gap layers 4 and 9 (which serve to maintain insulation between the shielding layers 1 and 10 and the magnetoresistive effect element 5), resulting in electric connection between the shielding layers 1 and 10 and the magnetoresistive effect element 5.
Particularly, the above-mentioned problem tends to be created between the electrode layer 8 having a large width formed on the rear side from the ABS plane and the shielding layers 1 and 10 as shown in FIG. 22, resulting in a lower reproducing property due to electric connection between the shielding layers 1 and 10 and the and the electrode layer 8.
Upon manufacturing a thin-film magnetic head, the ABS plane of the multilayer film 6 is ground (height-making fabrication in the height direction (Y-direction in FIG. 22)) until a specified DC resistance of the multilayer film 6 (shown in FIG. 22) is obtained. This height-making fabrication causes smearing between the shielding layers 1 and 10 and the electrode layer 8, tending to make electric connection between the shielding layers 1 and 10 and the electrode layer 8.
When the shielding layers 1 and 10 and the electrode layer 8 are electrically connected, the height-making fabrication cannot be applied because of inaccurate measuring of the DC resistance of the multilayer film 6.
The present invention was developed for the purpose of solving the conventional problems as described above, and relates to a thin-film magnetic head which can maintain an appropriate electric insulation between the shielding layer and electrode layer of the magnetoresistive effect element even for a small gap length and permits obtaining a stable reproducing property, thereby coping with the tendency toward a higher recording density, and a manufacturing method thereof.
The present invention provides a thin-film magnetic head comprising a lower shielding layer and a lower gap layer formed thereon, a magnetresistive element comprising a multilayer film displaying magnetoresistive effect and formed on said lower gap layer and an electrode layer connected to said multilayer film, and an upper shielding layer formed on the magnetoresistive effect element via the upper gap layer; wherein an insulating layer is formed in addition to the lower gap layer between the electrode layer and the lower shielding layer.
In the invention, the insulating layer should preferably be arranged a least on each side of the multilayer film or a reproducing track width.
In the invention, furthermore, the lower gap layer and the insulating layer should preferably have a total thickness of at least 700 xc3x85.
In a detailed structure in the invention, an insulating layer should preferably be formed on the lower shielding layer, and the electrode layer should preferably be formed on the insulating layer with the lower gap layer interposed therebetween.
A slant should preferably be formed on each of the sides of the insulating layer.
In the invention, the insulating layer should preferably be formed with one or more insulating materials selected from the group consisting of SiO2, Al2O3, Ta2O5, TiO, Ti2O3, Ti3O5, WO3, Si3N4 and AlN.
In a detailed structure in the invention, a recess should preferably be formed on the surface of the lower shielding layer, with an insulating layer formed in the recess, and the electrode should preferably be formed on the insulating layer with the lower gap layer interposed therebetween.
In this case, the surface of the lower shielding layer should preferably be flush with the surface of the insulating layer formed in the recess of the lower shielding layer.
In the invention, the insulating layer formed under the electrode layer should preferably be formed by exposing up to an ABS plane.
As in the configuration described above, in the invention, it is possible to maintain a satisfactory level of electric insulation between the electrode layer and the shielding layer by forming an insulating layer, in addition to the lower gap layer, between the electrode layer and the lower shielding layer.
The invention further provides a thin-film magnetic head comprising a lower shielding layer and a lower gap layer formed thereon, a magnetoresistive effect element comprising a multilayer film displaying magnetoresistive effect and formed on said lower gap layer and an electrode layer connected to multilayer film, and an upper shielding layer formed on the magnetoresistive effect element with the upper gap layer interposed therebetween; wherein an insulating layer is formed in addition to the upper gap layer between the electrode layer and the upper shielding layer.
In the invention, the insulating layer should preferably be arranged at least on each of the both sides of the multilayer film or a reproducing track width.
In the invention, furthermore, the lower gap layer and the insulating layer should preferably have a total thickness of at least 700 xc3x85.
In the invention, an insulating layer should preferably be formed on the electrode layer with the upper gap layer interposed therebetween. A slant should preferably be formed on each of the sides of the insulating layer.
In the invention, furthermore, the insulating layer should preferably be formed with one or more insulating materials selected from the group consisting of SiO2, Al2O3, Ta2O5, TiO, Ti2O3, Ti3O5, WO3, Si3N4 and AlN.
In another detailed structure in the invention, an insulating layer should preferably be formed on the electrode layer, and further, an upper gap layer should preferably be formed on the insulating layer.
In the invention, the insulating layer formed on the electrode layer should preferably be formed by exposing up to an ABS plane.
As in the above-mentioned configuration of the invention, it is possible to maintain a satisfactory level of electric insulation between the electrode layer and the shielding layer by forming the insulating layer, in addition to the upper gap layer, between the electrode layer and the upper shielding layer.
The present invention further provides a thin-film magnetic head comprising a lower shielding layer and a lower gap layer formed thereon, a magnetoresistive effect element having a multilayer film formed on the lower gap layer and connected to the multilayer film, and an upper shielding layer formed on the magnetoresistive effect element via the upper gap layer; wherein the insulating layer is formed between the electrode layer and the lower shielding layer, and the insulating layer is formed between the electrode layer and the upper shielding layer.
Further, the invention provides a manufacturing method of a thin-film magnetic head, comprising:
a step of forming an insulating material layer on a lower shielding layer;
a step of forming a resist layer on the insulating material layer;
a step of removing the insulating material layer not covered with the resist layer to retain the insulating material layer formed under the resist layer as an insulating layer;
a step of forming a lower gap layer on an area covering the insulating layer and the lower shielding layer, after removing the resist layer;
a step of forming an electrode layer of a magnetoresistive effect element on the lower gap layer overlapping the insulating layer, and forming a multilayer film displaying magnetoresistive effect on the lower gap layer; and
a step of forming an upper gap layer on the magnetoresistive effect element formed on the lower gap layer, and forming an upper shielding layer on the upper gap layer.
When using the above-mentioned manufacturing method, it is recommendable to form a slant on a side of the insulating layer retained under the resist layer by the use of isotropic etching after forming the resist layer on the insulating material layer.
Or, it is desirable to form a resist layer on the insulating material layer, then, form a slant on a side of the resist layer surface by applying a heat treatment to the resist layer, and form a slant on the other side of the insulating layer under the resist layer by the use of anisotropic etching.
In order to use isotropic etching or anisotropic etching, it is desirable to form the insulating material layer with one or more insulating materials selected from the group consisting of SiO2, Al2O3, Ta3O5, TiO, Ti2O3, Ti3O5, WO3, Si3N4 and AlN.
In the present invention, the aforementioned method for forming the insulating layer upon forming the insulating layer on the electrode layer with the upper gap layer interposed therebetween.
The invention further provides a manufacturing method of a thin-film magnetic head, comprising:
a step of forming a resist layer for lifting off on a lower shielding layer;
a step of forming a recess on the surface of the lower shielding layer by applying etching to the surface of the lower shielding layer not covered with the resist layer;
a step of forming an insulating layer in the recess formed on the surface of the lower shielding layer;
a step of removing the resist layer and forming a lower gap layer on an area covering the insulating layer and the lower shielding layer;
a step of forming an electrode layer of a magnetoresistive effect element on the lower gap layer overlapping the insulating layer, and forming a multilayer film displaying a magnetoresistive effect on the lower gap layer not having an insulating layer formed thereon; and
a step of forming an upper gap layer on the magnetoresistive effect element formed on the lower gap layer, and further, forming an upper shielding layer on the upper gap layer.
When using the aforementioned manufacturing method, it is desirable to form the insulating layer in a recess formed on the lower shielding layer so that the surface of the insulating layer is flush with the surface of the lower shielding layer.
By using the aforementioned manufacturing method, it is possible to easily form the insulating layer between the shielding layer and the electrode layer, and hence, to achieve satisfactory electric insulation between the shielding layer and the electrode layer.
The present invention further provides a manufacturing method of a thin-film magnetic head, comprising:
a step of forming a multilayer film displaying a magnetoresistive effect on the entire surface of the lower gap layer;
a step of forming a lift-off resist layer on the multilayer film, and removing the multilayer film not covered with the lift-off resist layer by etching;
a step of forming an electrode layer on the lower gap layer, from which the multilayer film has been removed in the preceding step, and forming an insulating layer on the electrode layer; and
a step of removing the lift-off resist layer, and forming the upper gap layer on an area covering the multilayer film and the insulating layer.
By using this method, it is possible to easily form the insulating layer in addition to the upper gap layer between the electrode layer and the upper shielding layer. According to the aforementioned method, furthermore, it is possible to completely cover the entire upper surface of the electrode layer with the insulating layer, thus permitting maintenance of a further better electric insulation between the upper shielding layer and the electrode layer.